This invention relates to a method of manufacturing a protective and decorative molding for an automobile, provided on a body of the automobile, and, in particular, to a method of making plastic foam molding by foaming plastic (resinous) materials to which foaming agent is added, in a mold.
Usually, elongated strips of decorative plastic moldings are provided on and adhered to side panels and/or door panels of an automobile to prevent the panel surfaces from being damaged when the automobile comes into collide with another automobile or the like, and for the purpose of decoration of side surfaces of the automobile body. This kind of plastic molding is usually made of an extruded solid material having a uniform cross section. Alternatively, a plastic foam molding has also been proposed, in place of the solid plastic molding obtained by a plastic extrusion process, in order to decrease the weight of the molding, and particularly the weight of a large and wide molding and to increase the elastic deformability i.e. shock absorptivity of the molding thereby to absorb a shock at the collision of the automobile. Furthermore, a highly decorative plastic molding is also known, which has different cross sectional shapes and which presents a good appearance especially at its extremeties. The different cross sectional shapes also contribute to increasing the shock absorptivity (elasticity) of the molding. It is very difficult to obtain such a highly decorative and deformable plastic molding by a conventional plastic extrusion method.
Various kinds of methods are known for manufacturing plastic foam products and particularly polyvinyl chloride (PVC)foam products. However, these known methods have drawbacks in that usable materials are limited to plastisol, or organosol or the like, a provisional foaming is required in addition to a finish forming, and complex foaming operations are required in the course of heating process, which increase the cost of manufacture and the number of operation steps.